The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Catalytic converters may reduce emissions in vehicles with an internal combustion engine. The catalytic converter may be a three-way catalytic converter and may include a substrate with a coating of catalyst materials. The catalytic converter may stimulate oxidation of hydrocarbons and carbon monoxide and reduction of nitrogen oxides. The catalysts may operate optimally when a temperature of the catalytic converter is above a minimum temperature that is in a range between 200° C. to 300° C. Emissions control using a catalytic converter may be difficult during a cold start because the catalytic converter has not reached the optimal temperature.
Catalytic converter warm-up (or “light-off”) time may be reduced during a cold start by generating high engine-out energy. The engine-out energy may be dependent on the exhaust temperature and mass flow rate of the exhaust. Retarding ignition timing and increasing engine idle speed may reduce cold start emissions by increasing exhaust temperature and mass flow rate. However, the impact of these strategies may be limited since retarding ignition timing lowers engine efficiency and may be perceived by the driver as approaching an engine stall.